They wont let you cancel your line

did cancellation forms on 11th Aug - 21 business days until contact but have received nothing to date. they are still sending me invoice and all I can do is escalate which I have done over 4 times! They just wont cancel my line and no one will help me - not even the call centers who I have to email my cancellation again to and who just escalate it. Its an absolute joke - CANCEL MY LINE!!!!